Evaluation and management of difficult-to-Treat and severe asthma: An expert opinion from the Korean Academy of asthma, allergy and clinical immunology, the working group on severe asthma

Severe asthma (SA) presents in about 3%–5% of adult asthmatics and is responsible for over 60% of asthma-related medical expenses, posing a heavy socioeconomic burden. However, to date, a precise definition of or clear diagnostic criteria for SA have not been established, and therefore, it has been challenging for clinicians to diagnose and treat this disease. Currently, novel biologics targeting several molecules, such as immunoglobulin E, interleukin (IL)5, and IL4/IL13, have emerged, and many new drugs are under development. These have brought a paradigm shift in understanding the mechanism of SA and have also provided new treatment options. However, we need to agree on a precise definition of and its diagnostic criteria for SA. Additionally, it is necessary to explain the diagnostic criteria and to summarize current standard and additional treatment options. This review is an experts' opinion on SA from the Korean Academy of Asthma, Allergy, and Clinical Immunology, the Working Group on Severe Asthma, and aims to provide a definition of and diagnostic criteria for SA, and propose future direction for SA diagnosis and management in Korea.